CN102116724A - Test method for thermal fatigue property of cast iron material - Google Patents

Test method for thermal fatigue property of cast iron material Download PDF

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Publication number
CN102116724A
CN102116724A CN2011100047076A CN201110004707A CN102116724A CN 102116724 A CN102116724 A CN 102116724A CN 2011100047076 A CN2011100047076 A CN 2011100047076A CN 201110004707 A CN201110004707 A CN 201110004707A CN 102116724 A CN102116724 A CN 102116724A
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China
Prior art keywords
temperature
sample
test
seconds
cast iron
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Pending
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CN2011100047076A
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Chinese (zh)
Inventor
李伟
邹德志
刘柯军
富壮
骆宗安
冯盈盈
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FAW Group Corp
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FAW Group Corp
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Priority to CN2011100047076A priority Critical patent/CN102116724A/en
Publication of CN102116724A publication Critical patent/CN102116724A/en
Pending legal-status Critical Current

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Abstract

The invention provides a test method for the thermal fatigue property of a cast iron material, which is used for testing the thermal fatigue property of a cast iron material. The test method comprises the following steps of: quickly raising the temperature of the minimum-diameter position of a circular arc segment in the middle of a test sample from room temperature to 450 DEG C within 7 s, maintaining the temperature at 450 DEG C for 90 s, reducing the temperature to 100 DEG C within 24 s, maintaining the temperature for 30 s, and circularly repeating temperature rise and temperature reduction between 100 DEG C and 450 DEG C in this way. The test method can be used for detecting the thermal fatigue times of the test sample in failure. The method provided by the invention is applicable to the testing of the thermal fatigue property of the cast iron material.

Description

A kind of test method of cast iron materials thermal fatigue property
Technical field
The present invention is a kind of method that is used to test the cast iron materials thermal fatigue property.
Background technology
The problem of thermal fatigue cracking often appears in cylinder cover of automobile engine, brake drum, and part material is a casting pig." the hot die steel thermal fatigue test method " that is applicable to hot die steel only arranged at present.Its principle is to utilize the high-frequency induction Fast Heating, utilizes methods such as pressurized air or spraying to be quickly cooled to lower limit temperature after reaching ceiling temperature.Sample has passed through certain cycle index and has produced the heat fatigue be full of cracks on the surface owing to constraint produces internal stress under the effect of thermal stress, this crackle is similar to the inefficacy be full of cracks of mould, is the method that the be full of cracks of simulation mould steel was lost efficacy.Also there is not at present a kind of method that is suitable for testing the cast iron materials thermal fatigue property.
Summary of the invention
The invention provides a kind of test method of cast iron materials thermal fatigue property, to solve the problem that does not also have a kind of suitable test cast iron materials thermal fatigue property method at present.
The technical scheme that the present invention takes is: comprise the following steps:
(1), arc section diameter in middle part is fixed on the comprehensive fatigue tester of thermal stress for minimum sample two ends by anchor clamps, and be connected with pressure transducer, this pressure transducer is used to measure sample in temperature the raise pressure that is produced when reducing, the variation of pulling force, also can judge whether to crack, at the sample middle part is that the minimum place of diameter connects thermopair, measures variation of temperature;
(2), energized makes the minimum position of sample middle part arc section diameter, be the resistance maximum in 7 second time, temperature is increased to 450 ℃ rapidly from room temperature, 450 ℃ of insulations after 90 seconds, is cooled to 100 ℃ with 24 seconds times, is incubated 30 seconds; Temperature is increased to 450 ℃ rapidly from room temperature in 7 second time then, after 90 seconds, is cooled to 100 ℃ with 24 seconds times 450 ℃ of insulations, is incubated 30 seconds, so reciprocation cycle between 100 ℃~450 ℃;
(3), sample when cracking equipment stops automatically, and the time and the test number (TN) of record operation.
The principle that invention produces heat fatigue is under the fixing operating mode in sample two ends, by the mode that adopts current flow heats make sample as shown in Figure 1 the minimum position of middle part arc section diameter, be that resistance maximum temperature raises, and generation compressive stress and certain plastic yield, air cooling reduces temperature then, and producing certain tension, circulation makes sample produce heat fatigue so repeatedly.Judge the quality of material opposing thermal fatigue property by the cold cycling number of times of duplicate when the thermal fatigue fracture.
We are set to 100 ℃~450 ℃ at each round-robin bound temperature of sample.Because lower limit temperature is the temperature of circulating cooling liquid under the cylinder cap duty for 100 ℃, 450 ℃ of the upper limits are cylinder cap maximum temperatures when operating at full capacity.Cast iron materials performance fall after surpassing this temperature increases simultaneously, is the inflection temperature of performance.
Sample heat time heating time is 7 seconds, is the fastest time of heating.Fast Heating during in order to the work of simulation cylinder cap.The ceiling temperature temperature retention time of sample is 90 seconds.Sample sample after ceiling temperature is incubated 90 seconds has been finished sufficient distortion under self retrains.This distortion can be observed by the measurement of compressive stress.Compressive stress does not have significant change after surpassing this time.Be 24 seconds to be to determine by the cooling power of anchor clamps according to sample the cool time of sample.The lower limit temperature temperature retention time of sample is 30 seconds.Sample sample after lower limit temperature is incubated 30 seconds has been finished sufficient distortion under self retrains.This distortion can be observed by the measurement of tension.Tension does not have significant change after surpassing this time.
The present invention is a Fast Heating under simulated automotive engine cylinder cover, the brake drum operating mode, utilizes the situation of self-condition heat radiation, in addition also in conjunction with cylinder cap and brake drum cylinder iron the characteristics of material developed this test method.This test method adopts high-power electric current Fast Heating, insulation and by anchor clamps conduction cooling sample is utilized and self retrains generation tension and compression stress, through repeatedly circulating under the tension and compression stress cracking, the quality of the situation of change evaluating material thermal fatigue property by cracking number of times and tension and compression stress; It is a kind of method of suitable test cast iron materials thermal fatigue property.
Description of drawings
Fig. 1 is the heat fatigue sample synoptic diagram that the present invention adopts;
Fig. 2 is a heat fatigue cold cycling synoptic diagram of the present invention;
Fig. 3 is experimental example thermal fatigue test of the present invention figure as a result.
Embodiment
(1), arc section diameter in middle part is fixed on the comprehensive fatigue tester of thermal stress for minimum sample two ends by anchor clamps, and be connected with pressure transducer, this pressure transducer is used to measure sample in temperature the raise pressure that is produced when reducing, the variation of pulling force, also can judge whether to crack, at the sample middle part is that the minimum place of diameter connects thermopair, measures variation of temperature;
(2), energized makes the minimum position of sample middle part arc section diameter, be the resistance maximum in 7 second time, temperature is increased to 450 ℃ rapidly from room temperature, 450 ℃ of insulations after 90 seconds, is cooled to 100 ℃ with 24 seconds times, is incubated 30 seconds; Temperature is increased to 450 ℃ rapidly from room temperature in 7 second time then, after 90 seconds, is cooled to 100 ℃ with 24 seconds times 450 ℃ of insulations, is incubated 30 seconds, so reciprocation cycle between 100 ℃~450 ℃;
(3), sample when cracking equipment stops automatically, and the time and the test number (TN) of record operation.
For realizing this test method needs: the comprehensive fatigue tester of thermal stress, test fixture, test sample, thermopair.The function of the comprehensive fatigue tester of thermal stress is the STRESS VARIATION of high-power electric current heating, the heating frequency of controlling sample, heating-up temperature, heat time heating time, firing rate, meter record cycle index, measurement sample.The effect of test fixture is clamping sample, heat radiation and is connected with the comprehensive fatigue tester of thermal stress.The shape of sample is seen Fig. 1.Its effect at first is that the high-power electric current by the comprehensive fatigue tester of thermal stress comes heating sample, because the area of sample arc section is less, according to formula P=I 2R is the heating power maximum at this position as can be known, so the firing rate of arc section is higher than other position of sample far away.But the sample holder end quick heat radiating that links to each other with the copper anchor clamps in addition.And the arc section middle part links to each other the temperature variation of may command sample with thermopair.Therefore by the comprehensive fatigue tester current flow heats of control thermal stress speed, heat time heating time, temperature retention time, cool time producing heat fatigue at the sample arc section so repeatedly, when crackle occurring, finish test, check that test number (TN) gets final product.
Experimental example
Adopt the gray cast iron material of this test method to two kinds of heterogeneities: casting pig 1, casting pig 2, every kind of 3 samples carry out thermal fatigue test.Test number (TN) the results are shown in Figure 3, and test findings can reflect the quality of material thermal fatigue property by the heat fatigue round-robin number of times that material carries out.

Claims (1)

1. the test method of a cast iron materials thermal fatigue property is characterized in that: comprise the following steps:
(1), arc section diameter in middle part is fixed on the comprehensive fatigue tester of thermal stress for minimum sample two ends by anchor clamps, and be connected with pressure transducer, this pressure transducer is used to measure sample in temperature the raise pressure that is produced when reducing, the variation of pulling force, also can judge whether to crack, at the sample middle part is that the minimum place of diameter connects thermopair, measures variation of temperature;
(2), energized makes the minimum position of sample middle part arc section diameter, be the resistance maximum in 7 second time, temperature is increased to 450 ℃ rapidly from room temperature, 450 ℃ of insulations after 90 seconds, is cooled to 100 ℃ with 24 seconds times, is incubated 30 seconds; Temperature is increased to 450 ℃ rapidly from room temperature in 7 second time then, after 90 seconds, is cooled to 100 ℃ with 24 seconds times 450 ℃ of insulations, is incubated 30 seconds, so reciprocation cycle between 100 ℃~450 ℃;
(3), sample when cracking equipment stops automatically, and the time and the test number (TN) of record operation.
CN2011100047076A 2011-01-11 2011-01-11 Test method for thermal fatigue property of cast iron material Pending CN102116724A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
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Application Number Priority Date Filing Date Title
CN2011100047076A CN102116724A (en) 2011-01-11 2011-01-11 Test method for thermal fatigue property of cast iron material

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Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102508143A (en) * 2011-10-26 2012-06-20 常州天合光能有限公司 Reliability test method for photovoltaic component
CN102519818A (en) * 2011-12-28 2012-06-27 昆明理工大学 Thermal fatigue performance test and analysis method for metal matrix composite material
CN102607979A (en) * 2012-03-30 2012-07-25 扬州大学 Vacuum glass thermal cycling fatigue test device
CN103900911A (en) * 2014-04-09 2014-07-02 西北工业大学 Electrified thermal stretching testing device and stretching testing method
CN106353214A (en) * 2016-08-23 2017-01-25 中国电力科学研究院 Method and system for performing thermal shock tests on transmission project outdoor galvanization armour clamp
CN106443230A (en) * 2016-08-23 2017-02-22 中国电力科学研究院 Thermal shock test system and method for transmission project outdoor galvanization fitting

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101105436A (en) * 2007-06-26 2008-01-16 上海大学 Hot fatigue performance test and analysis method for steel
JP2009128171A (en) * 2007-11-22 2009-06-11 Toyota Motor Corp Heat resistant material testing device, heat resistant material test method, and test piece
CN201681029U (en) * 2010-01-06 2010-12-22 湘潭大学 Testing device for simulating and testing failure of heat fatigue of high-temperature parts in real time

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101105436A (en) * 2007-06-26 2008-01-16 上海大学 Hot fatigue performance test and analysis method for steel
JP2009128171A (en) * 2007-11-22 2009-06-11 Toyota Motor Corp Heat resistant material testing device, heat resistant material test method, and test piece
CN201681029U (en) * 2010-01-06 2010-12-22 湘潭大学 Testing device for simulating and testing failure of heat fatigue of high-temperature parts in real time

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102508143A (en) * 2011-10-26 2012-06-20 常州天合光能有限公司 Reliability test method for photovoltaic component
CN102519818A (en) * 2011-12-28 2012-06-27 昆明理工大学 Thermal fatigue performance test and analysis method for metal matrix composite material
CN102607979A (en) * 2012-03-30 2012-07-25 扬州大学 Vacuum glass thermal cycling fatigue test device
CN102607979B (en) * 2012-03-30 2013-10-02 扬州大学 Vacuum glass thermal cycling fatigue test device
CN103900911A (en) * 2014-04-09 2014-07-02 西北工业大学 Electrified thermal stretching testing device and stretching testing method
CN103900911B (en) * 2014-04-09 2016-06-29 西北工业大学 A kind of energising hot tensile test device and stretching test method
CN106353214A (en) * 2016-08-23 2017-01-25 中国电力科学研究院 Method and system for performing thermal shock tests on transmission project outdoor galvanization armour clamp
CN106443230A (en) * 2016-08-23 2017-02-22 中国电力科学研究院 Thermal shock test system and method for transmission project outdoor galvanization fitting
CN106443230B (en) * 2016-08-23 2020-03-13 中国电力科学研究院 Thermal shock test system and method for outdoor current-carrying hardware in power transmission project

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Application publication date: 20110706